Check for available connection first?

[Jeff Hedlund]

To work around my problem in this post -> https://sourceforge.net/forum/message.php?msg_id=7531953

I'm wondering, is there a way I can detect if there are any available ports to connect to before I attempt the connection?

So I've got this running on the server:

  com2tcp-rfc2217.bat COM6 5555

I connect with one client computer.

With a second client computer, can I issue a command that tells me that the server already has 1 connection so I don't attempt another connection?

Jeff

[Jeff Hedlund]

In addition to working around my other problem, this would let me possibly script something to tell the end user on the failing client computer "COM pool is at capacity"

Jeff

[Vyacheslav Frolov]

To the CVS version of hub4com added ability to set priority
for listen ports. Now you can add a fake listen port with low
priority and route it to simple server that will tell "All ports busy"
and disconnect.

See also:

hub4com --help=tcp

[Jeff Hedlund]

Thanks very much for this, I am incorporating it now!

Jeff

[Jeff Hedlund]

Vyacheslav,

I have been playing with this by using the QUOTE server (RFC 865) that just returns a quote of the day and disconnects, and the hub4com client is not seeing the quote echo'd back to it. 

Config looks like:

------------------------------------------
COM3
--use-driver=tcp
*5555
--bi-route=0:1

5555/-1
--bi-route=3:2
127.0.0.1:17
------------------------------------------

When I connect the 2nd client, the client sees some output from hub4com with this at the end:

TCP(1) SEND: SB 44
  5 6 SE
ReadOverlapped::StartRead(): ReadFileEx(778) TCP(1) ERROR Unknown error (64)

On the server, I see this:

TCP(2): Accept(778) = 740 from 192.168.50.10:3144
Socket(0.0.0.0:0) = 730
TCP(3): Connect(730, 127.0.0.1:17) ...
TCP(3): Close(730) - OK
TCP(2): Disconnect(740) - OK
ReadOverlapped::OnRead(): TCP(2) ERROR Unknown error (64)
ReadOverlapped::StartRead(): ReadFileEx(740) TCP(2) ERROR Unknown error (64)
TCP(2): Close(740) - OK

Any guidance?

Thanks!
Jeff

[Vyacheslav Frolov]

Possible it's because the connection is reset before all data sent.
Try to replace line 257 in plugins\tcp\comio.cpp

  if (shutdown(hSock, SD_BOTH) != 0)

to

  if (shutdown(hSock, SD_SEND) != 0)

[Jeff Hedlund]

> Try to replace line 257 in plugins\tcp\comio.cpp
> 
> if (shutdown(hSock, SD_BOTH) != 0) 
> to
> if (shutdown(hSock, SD_SEND) != 0)

Tried this and it resulted in an infinite loop trying to connect from the client.

Jeff

[Vyacheslav Frolov]

It's because of sign *